学习目标

学习openGauss体系结构，了解实例（集簇或服务）和数据库的关系

作业

1.创建表空间music_tbs1和多个数据库music_db、music_db1、music_db2

--创建表空间music_tbs1
openGauss=# CREATE TABLESPACE music_tbs RELATIVE LOCATION 'tablespace/test_ts1';
CREATE TABLESPACE

可以看到在pgdata 的 pg_tblspc下面生成了该表空间的ln，同时在ln对应的目录下生成了相关文件
[omm@og3 dn]$ cd pg_tblspc/
[omm@og3 pg_tblspc]$ ls -ltr
total 0
lrwxrwxrwx. 1 omm dbgrp 49 Nov 28 23:21 16390 -> /datafs/ogdata/dn/pg_location/tablespace/test_ts1

--创建3个数据库
openGauss=# CREATE DATABASE musicdb  WITH TABLESPACE = music_tbs;
CREATE DATABASE
openGauss=# CREATE DATABASE musicdb1 WITH TABLESPACE = music_tbs;
CREATE DATABASE
openGauss=# CREATE DATABASE musicdb2 WITH TABLESPACE = music_tbs;

2.查看数据库上的表空间
pg_default、 pg_global为默认的表空间在data目录下不显示路径

openGauss=# \db
           List of tablespaces
    Name    | Owner |      Location
------------+-------+---------------------
 music_tbs  | omm   | tablespace/test_ts1
 pg_default | omm   |
 pg_global  | omm   |
(3 rows)

3.查看openGauss实例上有哪些数据库

--通过pg_database视图查看详细的信息
openGauss=#  select *  from pg_database;
  datname  | datdba | encoding | datcollate | datctype | datistemplate | datallowconn | datconnlimit | datlastsysoid | datfrozenxid | dattablespace | datcompatibility |        datacl        | datfro
zenxid64 | datminmxid
-----------+--------+----------+------------+----------+---------------+--------------+--------------+---------------+--------------+---------------+------------------+----------------------+-------
---------+------------
 template1 |     10 |        0 | C          | C        | t             | t            |           -1 |         15619 | 0            |          1663 | A                | {=c/omm,omm=CTc/omm} |
   13017 |          2
 musicdb   |     10 |        0 | C          | C        | f             | t            |           -1 |         15619 | 12662        |         16390 | A                |                      |
   12662 |          2
 musicdb1  |     10 |        0 | C          | C        | f             | t            |           -1 |         15619 | 12662        |         16390 | A                |                      |
   12662 |          2
 template0 |     10 |        0 | C          | C        | t             | f            |           -1 |         15619 | 0            |          1663 | A                | {=c/omm,omm=CTc/omm} |
   12662 |          2
 musicdb2  |     10 |        0 | C          | C        | f             | t            |           -1 |         15619 | 12662        |         16390 | A                |                      |
   12662 |          2
 postgres  |     10 |        0 | C          | C        | f             | t            |           -1 |         15619 | 0            |          1663 | A                |                      |
   13372 |          2
(6 rows)

--也可以通过\l查看
openGauss=# \l
                          List of databases
   Name    | Owner | Encoding  | Collate | Ctype | Access privileges
-----------+-------+-----------+---------+-------+-------------------
 musicdb   | omm   | SQL_ASCII | C       | C     |
 musicdb1  | omm   | SQL_ASCII | C       | C     |
 musicdb2  | omm   | SQL_ASCII | C       | C     |
 postgres  | omm   | SQL_ASCII | C       | C     |
 template0 | omm   | SQL_ASCII | C       | C     | =c/omm           +
           |       |           |         |       | omm=CTc/omm
 template1 | omm   | SQL_ASCII | C       | C     | =c/omm           +
           |       |           |         |       | omm=CTc/omm
(6 rows)

4.使用操作系统命令，查看openGauss实例的进程、线程

[root@og3 ~]# ps -eaf|grep omm
root      63760  61329  0 22:55 pts/1    00:00:00 su - omm
omm       63761  63760  0 22:55 pts/1    00:00:00 -bash
omm       66149      1  5 22:58 ?        00:01:48 /datafs/og3/app/bin/gaussdb -D /datafs/ogdata/dn
omm       68027  63761  0 23:17 pts/1    00:00:00 gsql -p 26000 -d postgres -r
root      69105  67832  0 23:34 pts/2    00:00:00 grep --color=auto omm
[root@og3 ~]# ps -Tp 66149
   PID   SPID TTY          TIME CMD
 66149  66149 ?        00:00:01 gaussdb
 66149  66150 ?        00:00:00 jemalloc_bg_thd
 66149  66155 ?        00:00:00 gaussdb
 66149  66156 ?        00:00:00 syslogger
 66149  66157 ?        00:00:00 alarm
 66149  66158 ?        00:00:00 reaper
 66149  66183 ?        00:00:00 checkpointer
 66149  66184 ?        00:00:00 Spbgwriter
 66149  66185 ?        00:00:07 pagewriter
 66149  66186 ?        00:00:00 pagewriter
 66149  66187 ?        00:00:00 pagewriter
 66149  66188 ?        00:00:00 pagewriter
 66149  66189 ?        00:00:00 pagewriter
 66149  66190 ?        00:00:00 WALwriter
 66149  66191 ?        00:00:00 WALwriteraux
 66149  66192 ?        00:00:00 AVClauncher
 66149  66193 ?        00:00:00 Jobscheduler
 66149  66194 ?        00:00:00 asyncundolaunch
 66149  66195 ?        00:00:00 globalstats
 66149  66196 ?        00:00:00 applylauncher
 66149  66197 ?        00:00:00 statscollector
 66149  66198 ?        00:00:00 txnsnapcapturer
 66149  66199 ?        00:00:00 CfsShrinker
 66149  66200 ?        00:00:05 percentworker
 66149  66201 ?        00:00:56 ashworker
 66149  66202 ?        00:00:16 TrackStmtWorker
 66149  66203 ?        00:00:00 auditor
 66149  66204 ?        00:00:00 2pccleaner
 66149  66205 ?        00:00:00 faultmonitor
 66149  66207 ?        00:00:04 undorecycler
 66149  68028 ?        00:00:00 worker